Charlie Veron is the world's leading expert on coral reefs. His prognosis for the future of the Great Barrier Reef, and the world, is dire.

Charlie Veron, the world's foremost expert on coral reefs, lives on a shady bend of Sachs Creek, half an hour's drive out of Townsville, in a concrete block house with three dogs, eight geese, two pet rats, seven cockatoos, a baby red fruit bat, scores of tropical fish, a green tree frog (in the bathroom), bush turkeys, the occasional echidna and what appears to be several million wallabies just about everywhere you look. Other animals include one son, two daughters and an adult female named Mary Stafford-Smith.

"The house is a bit of a menagerie," says Stafford-Smith, who also happens to be Veron's wife. "There are dingoes in the valley, too. Once we found a pup under a bush in the garden and looked after it."

The house, which is called Rivendell, after the elves' hidden refuge in J. R. R. Tolkien's The Lord of the Rings, is part of Veron's being. He built much of it by hand, and has lived here for 40 years. (Stafford-Smith, also an expert coral biologist, has been here for 30.) Recently, however, he has been thinking about moving, perhaps to the Atherton Tablelands near Cairns, where it is cooler, wetter and higher, and thus more likely to cope with climate change – the cataclysmic wrath of which will be upon us, Veron believes, in 10 to 15 years.

Dr Charlie Veron at favourite spot at home near Townsville. Photo: Wolter Peeters

"We have crossed a bridge now, and we have burnt it," he says, sitting on his patio overlooking the creek, eating a ham and cheese roll. Moving out, should it come to that, will be a mixed challenge. The 72-year-old Veron is a veteran "chucker-outtera": apart from a defunct pool table and his father's army dress sword, he has few material possessions. He gets his clothes from Vinnies ("the best shop in the world"), doesn't own a pair of formal shoes and has successfully purged his home of coral specimens, which remind him of work.

Shifting his library, on the other hand, could be trickier. Rivendell is stuffed with books, thousands of titles on everything from Giuseppe Verdi to Lawrence of Arabia. But most of his collection concerns marine biology and coral, a topic Veron knows more about than anybody on the planet. Dubbed the "Godfather of Coral", Veron has, over his 50-year career, redefined our understanding of reefs, the way they grow and reproduce, the way they evolve, and now, most poignantly, the way they are dying. He has identified more than 20 per cent of the world's coral species, and has been likened by David Attenborough to a modern-day Charles Darwin.

"His contribution has been huge," says the scientist, explorer and conservationist Tim Flannery. "Without his early work we wouldn't have had the basic benchmarks to see the nature of the changes that we are now seeing. He provided that baseline to put everything in context." Author and environmental advocate Tim Winton says Veron "isn't just a coral scientist, he's a pathfinder, a scout who's been sending back dispatches on the future of our planet for decades. If ever there was a moment for Australians to listen up and act on what he's learnt, it's now."

A reef flat exposed at low tide on the Great Barrier Reef, which is under severe threat from climate-change. Photo: Courtesy of Penguin Random House Australia

Veron is a journalist's dream: highly knowledgeable, and fearlessly outspoken. He has of late become the go-to guy for anyone seeking a frank opinion about coral bleaching on the Great Barrier Reef. "The reef is in strife, and to say otherwise is bullshit," he tells me at Rivendell. "Half the place is dead already. It won't be here in 15 years." Contrary to public opinion, he says, runoff from nearby farms is not nearly as big a threat to the reef as climate change, embodied most recently in the proposed Carmichael coal mine, in north central Queensland. The mine's proponent, the Indian multinational conglomerate Adani, projects there will be more than 4.7 billion tonnes of carbon dioxide emissions associated with the mine over its lifetime – nine times Australia's total production of the greenhouse gas in 2015.

Veron has variously referred to Carmichael as "evil", "beyond logic" and "appallingly stupid". The larger problem is not the mine, as bad as that is. It's Australia, it's the world; it's our complacency, our distrust of science and, of course, it's our politicians. "We are being led by idiots," Veron says. Former federal environment minister Greg Hunt is "the most stupid man you could ever hope to meet". Tony Abbott is a "moron"; Queensland Premier Annastacia Palaszczuk, who has also backed the mine, "just awful". Prime Minister Malcolm Turnbull, he says, is the worst of the lot. "A few years ago I talked to him for two hours about climate change, and he had a great grasp of it. Then he turns around and does nothing. To me, that is truly criminal."

Scientists are, by nature, cautious. Instead of opinions, they have facts. Instead of randomness and speculation, they have reason and protocol. Veron is largely the opposite. He abhors protocol and is falling over himself with opinions, many of which have found their way into his new book, A Life Underwater. Equal parts memoir, coral reef primer and requiem to a planet, Veron's book charts a career that could scarcely be imagined today, a love affair with science birthed from childhood wonderment, free-range academia and happy accidents.

Born and raised in Sydney's north, Veron was an awkward child: he suffered from asthma and a pronounced stammer. He spent most of his time roaming nearby bushland or poring for hours over rock pools at Long Reef beach. Veron (whose real first name is John) had a habit of bringing his discoveries into class – sea worms, funnel web spiders – prompting his teacher to dub him Mr Darwin, or Charlie. He attended Barker College, a private school, where he failed miserably in everything except biology.

In his final year, however, he took part in a one-off government experiment to test whether IQ results could predict university performance better than school leaving exams. To Veron's amazement, he topped them all, and was offered a Commonwealth scholarship to the university of his choosing. He opted for the University of New England, in country NSW, mostly because it was away from the cities.

"Because of his results at school, Charlie felt he had a lot to prove," says his first wife Kirsty, who met Veron at university. "He felt he had to carve out a niche."

"A few years ago I talked to [Prime Minister Malcolm Turnbull] for two hours about climate change, and he had a great grasp of it. Then he turns around and does nothing. To me, that is truly criminal."

Veron studied herpetology and entomology. He was about to move to Canada to study locusts when Kirsty came upon an advertisement for postdoc work on corals, based at James Cook University in Townsville. Veron knew virtually nothing about corals but, remembering his time at Long Reef, applied for the position. Little did he know, his was the sole application. Thus he set two unlikely records: being appointed the Great Barrier Reef's first full-time research scientist, and becoming a marine biologist without ever having attended a single lecture on marine biology.

Veron is slight and wiry; he has a deeply guttered face, grey hair and piercing blue eyes. He is mesmerically articulate, given to long, discursive tutorials on everything from the endurance of coral larvae to the carbon cycle. He can also be petulant – "No one ever listens to me, I'm just a marine scientist" – and prone to the odd, discordant analogy. (At one point he likens himself to "an Aborigine", due to his ability to enter meditative, nature-induced trances.)

"Charlie is eccentric," says the University of Queensland marine scientist Ove Hoegh-Guldberg. "He is also a very personal and focused individual. Lots of pioneers are like that. They don't work well in groups."

Veron's achievements are, quite literally, unprecedented. He was the first to compile a global taxonomy of corals – a monumental task that effectively became the cornerstone for all later learning. He was the first to show that, contrary to received wisdom, the Indo-Philippines archipelago has the world's greatest diversity of coral, not the Great Barrier Reef. He was instrumental in identifying the Coral Triangle – the so-called "Amazon of the seas" – a 5.7-million-square-kilometre area from the Solomon Islands in the east to Brunei in the west, which is now recognised as the world's centre of marine biodiversity and a global priority for conservation.

He also originated a whole new theory about how corals evolved – which is kind of a big thing. Reticulate evolution, as it's known, was born in large part from coral's taxonomic complexity, and the profusion of what scientists call cryptic species. "With land animals, you can hold a mouse in your hand and say, 'This is a mouse,' " Hoegh-Guldberg explains. "What Charlie discovered is that coral can go back and forth between one species and another." Darwinian evolution describes how, over time, animals diverge from one another into discrete and permanent species. Reticulate evolution describes how the ocean environment has made the boundaries between marine species, such as coral, much more "fuzzy".

"On land, there are barriers like mountain ranges, which are semi-permanent, which lead to animals in one part evolving differently to those in another part," Hoegh-Guldberg says. "But the ocean is a much more fluid environment. There are changes in currents and water temperatures, El Niños, everything. As a result, species boundaries in water change more frequently, quick enough even to disrupt full species emergence."

Veron's theory was revolutionary: when he published it, in his 1995 book Corals in Space and Time, the journal Science devoted an article to it, and he later received the prestigious Darwin Medal from the International Society for Reef Studies. While reticulate evolution has found a permanent place in the universe of ideas, the academic environment that produced it – a robust culture of free and independent inquiry – is fast disappearing, according to Veron. "The demise of academia in this country is horrific," he says.

When Veron arrived at James Cook University, the head of the biological sciences department waved vaguely in the direction of the Great Barrier Reef, and told him: "Your job is to go out there … and do something," adding as an afterthought: "And try to stay out of trouble." Veron was granted similar independence when, in the mid-'70s, he became the first full-time scientist employed by the newly formed Australian Institute of Marine Science. Back then, AIMS was rambunctious and non-hierarchical, home to a hardworking, free-wheeling culture that put results before rules. "Like all scientists, we worked best that way, when we were left alone," he says.

Before long, however, Veron began noticing an increasing number of meetings to attend, committees to report to and forms to fill out. "The place was becoming run by bureaucrats who kept on coming up with more rules and regulations, because that is what gave them work and kept them employed." By the time Veron became AIMS's chief scientist in 1996, the situation was "out of control". Every AIMS staffer who returned from a dive, for example, was required to fill out a long, complicated form logging, among other things, tide, visibility, water temperature, wind, currents, and the number of fish they had sighted.

"Unless you come across something noteworthy, recording all that data is utterly useless," Veron says. "It would never be read, it was all just put together by some guy in a computer centre who couldn't even swim." One day Veron switched the whole system off. "Just like that," he says. "Not that it helped, because by that time, the culture was gone." Veron left AIMS in 2007. "It's got even worse, from what I hear," he says. "The scientists there are told what to work on, when to work on it, for how long and with what resources." He believes the institute should be shut down.

"People there don't discover things anymore," he says, before adding. "Just imagine if Darwin had to work in that system. He would have been stomped on long ago." (CEO John Gunn says, "AIMS has certainly changed since Charlie left, but I'd suggest that most organisations have evolved, and that AIMS has been very successful. Charlie was a legend at AIMS, and always will be revered as a pioneer.")

Veron can make for depressing company. While his rapture at the natural world remains intact, he has become fixated on climate change, the effects of which, he believes, are now irreversible. "It's a catastrophe," he says. "We are looking at a future that is barely comprehensible. There will be immense social disruption, mass starvation, resource wars, cyclones the likes of which we've never experienced. Mass extinctions. And it's going to happen much sooner than people think." For parents of young children, Veron's message is particularly grim. "Don't imagine that your kids will have a life like yours, because they won't."

Veron has borne the brunt of what the American Psychological Association calls "eco-anxiety": a despair at the future of the planet so deep it can cause depression, grief, stress, even suicide. Stafford-Smith, Veron's wife, says, "There is a quite high rate of depression among scientists. We see it ourselves. We have been trying to get the message out for 30 years. We are going over a precipice, and there's nothing we can do about it."

Veron's pessimism is informed by his 50-year love affair with the reef, says Tim Flannery. "Charlie has watched one of the world's greatest assemblages collapse around him, in his lifetime." (Flannery, it's worth noting, is more hopeful than Veron, whom he says "would not be aware of the potential ways we will be able to draw CO² out of the atmosphere with carbon-negative silicon rocks and making plastic with atmospheric CO² ".) Not that Veron has given up: in the past 18 months, he has given 67 interviews about climate change and the state of the Great Barrier Reef, and has also taken part in the documentary Chasing Coral. And yet, in a moment that would make Eeyore proud, he tells me that it's only made things worse.

"It's like having a child with a terminal illness, and you're talking about it over and over." It's no fun, then, chez Veron. When I tell him I live near the beach, he suggests I sell up and move before storm surges make my house unviable. "I make an analogy with being Jewish in Nazi Germany in the 1930s," he says. "I'd say, 'Move, move now! Don't worry about getting a good price for your house, just go. In 10 years' time, everyone will be moving and it'll be too expensive.' "

Before I leave, Veron leads me down to the banks of the creek in front of his home, to a cool, shady spot overhung with the branches of a giant fig tree. He leans against the tree's roots and tells me about how, when he was a boy, he would sit for hours in a beautiful place, in the bush usually, and do nothing. He would just sit there and breath, and drift off. And not think. At all. "Not thinking is such a gift," he says.

As he grew older, though, not thinking became harder to do. "Now I'm trying to get that back, the ability to not think." We both stare in silence at the creek, which has tiny bubbles on its surface which pop, and are replaced by other tiny bubbles. Then we go back up to the house for a cup of tea.

Charlie Veron's A Life Underwater (Penguin Random House, $35) is published on Monday.